Documentation of USB 3.0

7/29/2019 Documentation of USB 3.0

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INTRODUCTIONUniversal Serial Bus (USB) is a serial bus standard to connect devices to a host

computer. The USB3.0 is the upcoming version of the USB. The USB 3.0 is also called superspeed USB. Because the USB 3.0 support a raw throughput of 500MByte/s. As its previous

versions it also support the plug and play capability, hot swapping etc. USB was designed to

allow many peripherals to be connected using a single standardized interface socket. . Other

convenient features include providing power to low-consumption devices, eliminating the need

for an external power supply; and allowing many devices to be used without requiring manufac-

turer-specific device drivers to be installed.

There are many new features included in the new Universal Serial Bus Specification. The

most important one is the supers speed data transfer itself. Then the USB 3.0 can support more

devices than the currently using specification which is USB 2.0. The bus power spec has been

increased so that a unit load is 150mA (+50% over minimum using USB 2.0). An unconfigured

device can still draw only 1 unit load, but a configured device can draw up to 6 unit loads

(900mA, an 80% increase over USB 2.0 at a registered maximum of 500mA). Minimum device

operating voltage is dropped from 4.4V to 4V. When operating in Super- Speed mode, full-

duplex signaling occurs over 2 differential pairs separate from the non-SuperSpeed differential

pair. This result in USB 3.0 cables containing 2 wires for power and ground, 2 wires for non-

Super- Speed data, and 4 wires for SuperSpeed data, and a shield (not required in previous

specifications).


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HISTORYPre-Releases:

USB 0.7: Released in November 1994.

USB 0.8: Released in December 1994.

USB 0.9: Released in April 1995.

USB 0.99: Released in August 1995.

USB 1.0: Released in November 1995.

USB 1.0

USB 1.0: Released in January 1996.Specified data rates of 1.5 Mbit/s (Low-Speed) and 12 Mbit/s (Full-Speed). Does not

allow for extension cables or pass-through monitors (due to timing and power

limitations). Few such devices actually made it to market.

USB 1.1: Released in September 1998.Fixed problems identified in 1.0, mostly relating to hubs. Earliest revision to be widely

adopted.

USB 2.0

USB 2.0: Released in April 2000.Added higher maximum speed of 480 Mbit/s (now called Hi-Speed). Further

modifications to the USB specification have been done via Engineering Change Notices

(ECN). The most important of these ECNs are included into the USB 2.0 specification

package available from USB.org:


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Mini-B Connector ECN: Released in October 2000.Specifications for Mini-B plug and receptacle. These should not be confused with

Micro-B plug and receptacle.

Pull-up/Pull-down Resistors ECN: Released in May 2002. Interface Associations ECN: Released in May 2003.

New standard descriptor was added that allows multiple interfaces to be associated

with a single device function.

Rounded Chamfer ECN: Released in October 2003.A recommended, compatible change to Mini-B plugs that results in longer lasting

connectors.

Inter-Chip USB Supplement: Released in March 2006. On-The-Go Supplement 1.3: Released in December 2006.

USB On-The-Go makes it possible for two USB devices to communicate with each

other without requiring a separate USB host. In practice, one of the USB devices acts

as a host for the other device.

Battery Charging Specification 1.0: Released in March 2007.Adds support for dedicated chargers (power supplies with USB connectors), host

chargers (USB hosts that can act as chargers) and the No Dead Battery provision which

allows devices to temporarily draw 100 mA current after they have been attached. If a

USB device is connected to dedicated charger, maximum current drawn by the device

may be as high as 1.8A. (Note that this document is not distrib- uted with USB 2.0

specification package.)

Micro-USB Cables and Connectors Specification 1.01: Released in April 2007. Link Power Management Addendum ECN: Released in July 2007.

This adds a new power state between enabled and suspended states. Device in this state is

not required to reduce its power consumption. However, switching between enabled and

sleep states is much faster than switching between enabled and suspended states, which

allows devices to sleep while idle.

High-Speed Inter-Chip USB Electrical Specification Revision 1.0: Released in September2007.


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USB 3.0

On September 18, 2007, Pat Gelsinger demonstrated USB 3.0 at the Intel

Developer Forum. The USB 3.0 Promoter Group announced on November 17, 2008,

that version 1.0 of the specification has been completed and is transitioned to the

USB Implementers Forum (USB-IF), the managing body of USB specifications. This

move effectively opens the spec to hardware developers for implementation in future

products.

Features

A new major feature is the "SuperSpeed" bus, which provides a fourth transfer modeat 4.8 Gbit/s. The raw throughput is 4 Gbit/s, and the specification considers it

reasonable to achieve 3.2 Gbit/s (0.4 GByte/s or 400 MByte/s) or more after protocol

overhead.

When operating in SuperSpeed mode, full-duplex signaling occurs over 2 differentialpairs separate from the non-SuperSpeed differential pair. This results in USB 3.0

cables containing 2 wires for power and ground, 2 wires for non-SuperSpeed data,

and 4 wires for SuperSpeed data, and a shield (not required in previous

specifications).

To accommodate the additional pins for SuperSpeed mode, the physical form factorsfor USB 3.0 plugs and receptacles have been modified from those used in previous

versions. Standard-A cables have extended heads where the SuperSpeed connectors

extend beyond and slightly above the legacy connectors. Similarly, the Standard-A

receptacle is deeper to accept these new connectors. On the other end, the SuperSpeed

Standard-B connectors are placed on top of the existing form factor. A legacy

standard A-to-B cable will work as designed and will never contact any of the

SuperSpeed connectors, ensuring backward compatibility. SuperSpeed standard A

plugs will fit legacy A receptacles but SuperSpeed standard B plugs will not fit into

legacy standard B receptacles (so a new cable can be used to connect a new device to

an old host but not to connect a new host to an old device; for that, a legacy standard

A-to-B cable will be required)


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SuperSpeed establishes a communications pipe between the host and each device, in ahost-directed protocol. In contrast, USB 2.0 broadcasts packet traffic to all devices.

USB 3.0 extends the bulk transfer type in SuperSpeed with Streams. This extensionallows a host and device to create and transfer multiple streams of data through a

single bulk pipe.

New power management features include support of idle, sleep and suspend states, aswell as Link-, Device-, and Function-level power management.

The bus power spec has been increased so that a unit load is 150 mA (+50% overminimum using USB 2.0). An unconfigured device can still draw only 1 unit load, but

a configured device can draw up to 6 unit loads (900 mA, an 80% increase over USB

2.0 at a registered maximum of 500 mA). Minimum device operating voltage is

dropped from 4.4 V to 4 V.

USB 3.0 does not define cable assembly lengths, except that it can be of any length aslong as it meets all the requirements defined in the specification. However,

electronicdesign.com estimates cables will be limited to 3 m at SuperSpeed.

Technology is similar to a single channel (1x) of PCI Express 2.0 (5-Gbit/s). It uses8B/10B encoding, linear feedback shift register (LFSR) scrambling for data and

spread spectrum. It forces receivers to use low frequency periodic signaling (LFPS),

dynamic equalization, and training sequences to ensure fast signal locking.

Connector properties

Availability

Consumer products are expected to become available in 2010. Commercial controllers

are expected to enter into volume production no later than the first quarter of 2010.On

September 24, 2009 Freecom announced a USB 3.0 external hard drive.

On October 27, 2009 Gigabyte Technology announced 7 new P55 chipsets

motherboards that included onboard USB 3.0, SATA Rev. 3 (6Gb/s) and triple power to all

USB ports.On January 6th, 2010 ASUS was the first manufacturer to release a USB 3.0-

certified motherboard, the P6X58D Premium.To ensure compatibility between motherboards


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and peripherals, all USB-certified devices must be approved by the USB Implementers

Forum.

Drivers are under development for Windows 7, but support was not included with the

initial release of the operating system.[57] The Linux kernel has supported USB 3.0 since

version 2.6.31, which was released in September 2009.

At least one complete end-to-end test system for USB3 designers is now on the

market.

Intel will not support USB 3.0 until 2011

which will slow down mainstream adoption. These delays may be due to problems in

the CMOS manufacturing process, a focus to advance the Nehalem platform or a tactic by

Intel to boost its upcoming Light Peak interface. Current AMD roadmaps indicate that the

new southbridges released in the beginning of 2010 will not support USB 3.0. Market

researcher In-Stat predicts a relevant market share of USB 3.0 not until 2011.

January 4, 2010, Seagate announced a small portable HDD with PC Card targeted

for laptops (or desktop with PC Card slot addition) at the CES in Las Vegas.

USB 3.0 Hub demo board using the VIA VL810 chip


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Usability

It is deliberately difficult to attach a USB connector incorrectly. Most connectorscannot be plugged in upside down, and it is clear from the appearance and kinesthetic

sensation of making a connection when the plug and socket are correctly mated.

However, it is not obvious at a glance to the inexperienced user (or to a user without

sight of the installation) which way around the connector goes, thus it is often

necessary to try both ways. More often than not, however, the side of the connector

with the tridentlogo should be on "top" or "toward" the user. Most manufacturers do

not, however, make the trident easily visible or detectable by touch.

Only moderate insertion / removal force is needed (by specification). USB cables andsmall USB devices are held in place by the gripping force from the receptacle

(without need of the screws, clips, or thumbturns other connectors have required).

The force needed to make or break a connection is modest, allowing connections to bemade in awkward circumstances (ie, behind a floor mounted chassis, or from below)

or by those with motor disabilities. This has the disadvantage of easily and

unintentionally breaking connections that one has intended to be permanent in case of

cable accident (e.g., tripping, or inadvertent tugging).

The standard connectors were deliberately intended to enforce the directed topologyof a USB network: type A connectors on host devices that supply power and type B

connectors on target devices that receive power. This prevents users from accidentally

connecting two USB power supplies to each other, which could lead to dangerously

high currents, circuit failures, or even fire.


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Durability

The standard connectors were designed to be robust. Many previous connectordesigns were fragile, specifying embedded component pins or other delicate parts

which proved liable to bending or breaks, even with the application of only very

modest force. The electrical contacts in a USB connector are protected by an adjacent

plastic tongue, and the entire connecting assembly is usually further protected by an

enclosing metal sheath. As a result USB connectors can safely be handled, inserted,

and removed, even by a young child.

The connector construction always ensures that the external sheath on the plug makescontact with its counterpart in the receptacle before any of the four connectors within

make electrical contact. The external metallic sheath is typically connected to system

ground, thus dissipating any potentially damaging static charges (rather than via

delicate electronic components). This enclosure design also means that there is a

(moderate) degree of protection from electromagnetic interference afforded to the

USB signal while it travels through the mated connector pair (this is the only location

when the otherwise twisted data pair must travel a distance in parallel). In addition,

because of the required sizes of the power and common connections, they are made

after the system ground but before the data connections.

The newer Micro-USB receptacles are designed to allow up to 10,000 cycles ofinsertion and removal between the receptacle and plug, compared to 1500 for the

standard USB and 5000 for the Mini-USB receptacle. This is accomplished by adding

a locking device and by moving the leaf-spring connector from the jack to the plug, so

that the most-stressed part is on the cable side of the connection.

Compatibility

The USB standard specifies relatively loose tolerances for compliant USB connectors,intending to minimize incompatibilities in connectors produced by different vendors

(a goal that has been very successfully achieved). Unlike most other connector

standards, the USB specification also defines limits to the size of a connecting device

in the area around its plug. This was done to prevent a device from blocking adjacent

ports due to the size of the cable strain relief mechanism (usually molding integral


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with the cable outer insulation) at the connector. Compliant devices must either fit

within the size restrictions or support a compliant extension cable which does.

Two-way communication is also possible. In USB 3.0, full-duplex communicationsare done when using SuperSpeed (USB 3.0) transfer. In previous USB versions (ie,

1.x or 2.0), all communication is half-duplex and directionally controlled by the host.

USB 3.0 receptacles are electrically compatible with USB 2.0 device plugs if they canphysically match. Most combinations will work, but there are a few physical

incompatibilities. However, only USB 3.0 Standard-A receptacles can accept USB 3.0

Standard-A device plugs.

In general, cables have only plugs (very few have a receptacle on one end), and hostsand devices have only receptacles. Hosts almost universally have type-A receptacles,

and devices one or another type-B variety. Type-A plugs mate only with type-A

receptacles, and type-B with type-B; they are deliberately physically incompatible.

Connector Types

Pinouts of Standard, Mini, and Micro USB

connectors


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Different types of USB connectors from left to right:

male micro USB

male mini USB B-type

male B-type

female A-type

male A-type

There are several types of USB connectors, including some that have been added

while the specification progressed. The original USB specification detailed Standard-A and

Standard-B plugs and receptacles. The first engineering change notice to the USB 2.0

specification added Mini-B plugs and receptacles.

The data connectors in the A - Plug are actually recessed in the plug as compared to

the outside power connectors. This permits the power to connect first which prevents data

errors by allowing the device to power up first and then transfer the data. Some devices will

operate in different modes depending on whether the data connection is made. This difference

in connection can be exploited by inserting the connector only partially. For example, some

battery-powered MP3 players switch into file transfer mode (and cannot play MP3 files)

while a USB plug is fully inserted, but can be operated in MP3 playback mode using USB

power by inserting the plug only part way so that the power slots make contact while the data

slots do not. This enables those devices to be operated in MP3 playback mode while getting

power from the cable.


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USB-A

The Standard-A type of USB plug is a flattened rectangle which inserts into a

"downstream-port" receptacle on the USB host, or a hub, and carries both power and data.

This plug is frequently seen on cables that are permanently attached to a device, such as one

connecting a keyboard or mouse to the computer via usb connection.

USB-B

A Standard-B plug which has a square shape with bevelled exterior corners typically

plugs into an "upstream receptacle" on a device that uses a removable cable, e.g. a printer. AType B plug delivers power in addition to carrying data. On some devices, the Type B

receptacle has no data connections, being used solely for accepting power from the upstream

device. This two-connector-type scheme (A/B) prevents a user from accidentally creating an

electrical loop.

Pin configuration of the USB connectors Standard A/B, viewed from face of plug


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Comparisons With Other Device Connection Technologies

FireWireUSB was originally seen as a complement to FireWire (IEEE 1394), which was

designed as a high-bandwidth serial bus which could efficiently interconnect peripherals such

as hard disks, audio interfaces, and video equipment. USB originally operated at a far lower

data rate and used much simpler hardware, and was suitable for small peripherals such as

keyboards and mice.

The most significant technical differences between FireWire and USB include the following:

USB networks use a tiered-star topology, while FireWire networks use a treetopology.

USB 1.0, 1.1 and 2.0 use a "speak-when-spoken-to" protocol. Peripherals cannotcommunicate with the host unless the host specifically requests communication. USB

3.0 is planned to allow for device-initiated communications towards the host (see

USB 3.0 below). A FireWire device can communicate with any other node at any

time, subject to network conditions.

A USB network relies on a single host at the top of the tree to control the network. Ina FireWire network, any capable node can control the network.

USB runs with a 5 V power line, while Firewire (theoretically) can supply up to 30 V. Standard USB hub ports can provide from the typical 500mA[2.5 Watts] of current,

only 100mA from non-hub ports.

USB 3.0 & USB On-The-Go 1800mA[9.0W] (for dedicated battery charging,1500mA[7.5W] Full bandwidth or 900mA[4.5W] High Bandwidth), while FireWire

can in theory supply up to 60 watts of power, although 10 to 20 watts is more typical.

These and other differences reflect the differing design goals of the two buses: USB

was designed for simplicity and low cost, while FireWire was designed for high performance,

particularly in time-sensitive applications such as audio and video. Although similar in

theoretical maximum transfer rate, FireWire 400 has performance advantage over USB 2.0

Hi-Bandwidth in real-use, especially in high-bandwidth use such as external hard-drives.

The newer FireWire 800 standard being twice as fast as FireWire 400 outperforms

USB 2.0 Hi-Bandwidth both theoretically and practically.The chipset and drivers used to


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implement USB and Firewire have a crucial impact on how much of the bandwidth

prescribed by the specification is achieved in the real world, along with compatibility with

peripherals.

Power over EthernetThe 802.3af Power over Ethernet has superior power negotiation and optimization

capabilities to powered USB. Power over Ethernet also supplies more power because it

operates at 48V, 720mA while USB operates at 5V, 500mA. Ethernet also operates many

more meters, with significant DC power loss, and will remain accordingly the preferred

option for VoIP, security camera and other applications where networks extend through a

building. However, USB is preferred when cost is critical.

Digital musical instrumentsDigital musical instruments are another example of where USB is competitive for low-cost

devices. However power over ethernet and the MIDI plug standard are preferred in high-end

devices that must work with long cables. USB can cause ground loop problems in audio

equipment because it connects the ground signals on both transceivers. By contrast, the MIDI

plug standard and ethernet have built-in isolation to 500V or more.

eSATA

The eSATA connector is a more robust SATA connector, intended for connection to external

hard drives and SSDs. It has a far higher transfer rate (3Gbps, bi-directional) than USB 2.0. A

device connected by eSATA appears as an ordinary SATA device, giving both full

performance and full compatibility associated with internal drives.

eSATA does not supply power to external devices. This may seem as a disadvantage

compared to USB, but in fact USB's 2.5W is usually insufficient to power external hard

drives. eSATAp (power over eSATA) is a new (2009) standard that supplies sufficient power

to attached devices using a new, backwards-compatible, connector.

eSATA, like USB, supports hot plugging, although this might be limited by OS drivers.


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Cables

The maximum length of a standard USB cable (for USB 2.0 or earlier) is 5.0 metres(16.4 ft). The primary reason for this limit is the maximum allowed round-trip delay of about

1,500 ns. If USB host commands are unanswered by the USB device within the allowed time,

the host considers the command lost. When adding USB device response time, delays from

the maximum number of hubs added to the delays from connecting cables, the maximum

acceptable delay per cable amounts to be 26 ns.

The USB 2.0 specification requires cable delay to be less than 5.2 ns per meter

(192,000 km/s, which is close to the maximum achievable bandwidth for standard copper

cable). This allows for a 5 meter cable. The USB 3.0 standard does not directly specify a

maximum cable length, requiring only that all cables meet an electrical specification. For

copper wire cabling, some calculations have suggested a maximum length of perhaps 3m.

No fiber optic cable designs are known to be under development, but they would be

likely to have a much longer maximum allowable length, and more complex construction.

The data cables for USB 1.x and USB 2.x use a twisted pair to reduce noise and

crosstalk. They are arranged much as in the diagram below. USB 3.0 cables are more

complex and employ shielding for some of the added data lines (2 pairs); a shield is added

around the pair sketched.

USB 1.x/2.0 cable wiring

Pin Name Cable color Description

1 VCC Red +5 V

2 D White Data

3 D+ Green Data +

4 GND Black Ground


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Pin Name Color Description

1 VCC Red +5 V

2 D White Data

3 D+ Green Data +

4 ID none permits distinction of

Micro-A- and Micro-B-Plug

Type A: connected to Ground

Type B: not connected

5 GND Black Signal Ground

USB 1.x/2.0 Miniplug/Microplug

Maximum Useful Distance

USB 1.1 maximum cable length is 3 metres (9.8 ft) and USB 2.0 maximum cable

length is 5 metres (16 ft). Maximum permitted hubs connected in series is 5. Although a

single cable is limited to 5 metres, the USB 2.0 specification permits up to five USB hubs in a

long chain of cables and hubs. This allows for a maximum distance of 30 metres (98 ft)

between host and device, using six cables 5 metres (16 ft) long and five hubs. In actual use,

since some USB devices have built-in cables for connecting to the hub, the maximum

achievable distance is 25 metres (82 ft) + the length of the device's cable. For longer lengths,USB extenders that use CAT5 cable can increase the distance between USB devices up to

50 metres (160 ft).

A method of extending USB beyond 5 metres (16 ft) is by using low resistance

cable.The higher cost of USB 2.0 Cat 5 extenders has urged some manufacturers to use other

methods to extend USB, such as using built-in USB hubs, and custom low-resistance USB

cable. It is important to note that devices which use more bus power, such as USB hard drives

and USB scanners will require the use of a powered USB hub at the end of the extension, so


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that a constant connection will be achieved. If power and data does not have sufficient power

then problems can result, such as no connection at all, or intermittent connections during use.

USB 3.0 cable assembly may be of any length as long as all requirements defined in

the specification are met. However, maximum bandwidth can be achieved across a maximum

cable length of approximately 3 metres.

Power

The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire from which

connected USB devices may draw power. The specification provides for no more than 5.25 V

and no less than 4.75 V (5 V5%) between the positive and negative bus power lines. For

USB 2.0 the voltage supplied by low-powered hub ports is 4.4 V to 5.25 V.

A unit load is defined as 100 mA in USB 2.0, and was raised to 150 mA in USB 3.0.

A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0, which was raised

to 6 (900 mA) in USB 3.0. There are two types of devices: low-power and high-power. Low-

power devices draw at most 1 unit load, with minimum operating voltage of 4.4 V inUSB 2.0, and 4 V in USB 3.0. High-power devices draw the maximum number of unit loads

supported by the standard. All devices default as low-power but the device's software may

request high-power as long as the power is available on the providing bus.

A bus-powered hub is initialized at 1 unit load and transitions to maximum unit loads

after hub configuration is obtained. Any device connected to the hub will draw 1 unit load

regardless of the current draw of devices connected to other ports of the hub (i.e one device

connected on a four-port hub will only draw 1 unit load despite the fact that all unit loads are

being supplied to the hub).

A self-powered hub will supply maximum supported unit loads to any device

connected to it. A battery-powered hub may supply maximum unit loads to ports. In addition,

the VBUSwill supply 1 unit load upstream for communication if parts of the Hub are powered

down.


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In Battery Charging Specification, new powering modes are added to the USB

specification. A host or hub Charging Downstream Port can supply a maximum of 1.5 A

when communicating at low-bandwidth or full-bandwidth, a maximum of 900 mA when

communicating at high-bandwidth, and as much current as the connector will safely handlewhen no communication is taking place; USB 2.0 standard-A connectors are rated at

1500 mA by default.

A Dedicated Charging Port can supply a maximum of 1.8 A of current at 5.25 V. A

portable device can draw up to 1.8 A from a Dedicated Charging Port. The Dedicated

Charging Port shorts the D+ and D- pins with a resistance of at most 200. The short

disables data transfer, but allows devices to detect the Dedicated Charging Port and allows

very simple, high current chargers to be manufactured.

Powered USB

Powered USB uses standard USB signaling with the addition of extra power lines. It

uses four additional pins to supply up to 6 A at either 5 V, 12 V, or 24 V (depending on

keying) to peripheral devices. The wires and contacts on the USB portion have been upgraded

to support higher current on the 5 V line, as well.

This is commonly used in retail systems and provides enough power to operate

stationary barcode scanners, printers, pin pads, signature capture devices, etc. This

modification of the USB interface is proprietary and was developed by IBM, NCR, and

FCI/Berg.

It is essentially two connectors stacked such that the bottom connector accepts a

standard USB plug and the top connector takes a power connector.

Sleep-and-charge

Sleep-and-charge USB ports can be used to charge electronic devices even when the

computer is switched off.


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USB 2.0 Data Rates

The theoretical maximum data rate in USB 2.0 is 480 Mbit/s (60 MB/s) per controller

and is shared amongst all attached devices. Some chipset manufacturers overcome this

bottleneck by providing multiple USB 2.0 controllers within the Southbridge. Big

performance gains can be achieved when attaching multiple high bandwidth USB devicessuch as disk enclosures in different controllers. The following table displays Southbridge ICs

that have multiple EHCI controllers.

Vendor Southbridge USB 2.0

Ports

EHCI

Controllers

Maximum

Data Rate

AMD SB7x0/SP5100 12 2 120 MB/s

AMD SB8x0 14 3 180 MB/s

Broadcom HT1100 12 3 180 MB/s

Intel ICH8 10 2 120 MB/s



Intel PCH 8/12/14 2 120 MB/s

nVIDIA ION/ION-LE 12 2 120 MB/s

Every other AMD, Broadcom, Intel southbridge supporting USB 2.0 has only one

EHCI controller. All SiS southbridge supporting USB 2.0 have only one EHCI controller. All

ULi, VIA southbridge, single chip northbridge/southbridge supporting USB 2.0 have only

one EHCI controller.

Also all PCI USB 2.0 ICs used for add-in cards have only one EHCI controller.

Despite that some card manufacturers offer improved cards which have 2 PCI USB 2.0 ICs

attached to one PCI to PCI bridge.


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In PCIe, the usual design with multiple USB ports per EHCI controller has changed

with the introduction of the MosChip MCS9990 IC. MCS9990 has one EHCI controller per

port so all its USB ports can operate simultaneously without any performance limitations.

Dual IC cards have been introduced as well and come with 2 PCI USB 2.0 ICs attached toone PCI to PCIe bridge.

Signaling

USB supports following signaling rates:

A low-bandwidth rate of 1.5 Mbit/s (~183 KB/s) is defined by USB 1.0. It is verysimilar to "full-bandwidth" operation except each bit takes 8 times as long to transmit.

It is intended primarily to save cost in low-bandwidth human interface devices (HID)

such as keyboards, mice, and joysticks.

The full-bandwidth rate of 12 Mbit/s (~1.43 MB/s) is the basic USB data rate definedby USB 1.1. All USB hubs support full-bandwidth.

A hi-bandwidth (USB 2.0) rate of 480 Mbit/s (~57 MB/s) was introduced in 2001.All hi-bandwidth devices are capable of falling back to full-bandwidth operation if

necessary; they are backward compatible. Connectors are identical.

A SuperSpeed (USB 3.0) rate of 4.8 Gbit/s (~572 MB/s). The written USB 3.0specification was released by Intel and partners in August 2008. The first USB 3

controller chips were sampled by NEC May 2009 and products using the 3.0

specification are expected to arrive beginning in Q3 2009 and 2010.USB 3.0

connectors are generally backwards compatible, but include new wiring and full

duplex operation.

Prior to USB 3.0, these collectively use half-duplex differential signaling to reducethe effects of electromagnetic noise on longer lines. Transmitted signal levels are 0.0

0.3 volts for low and 2.83.6 volts for high in full-bandwidth and low-bandwidth

modes, and 1010 mV for low and 360440 mV for high in hi-bandwidth mode.

A USB connection is always between a host or hub at the "A" connector end, and a


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device or hub's "upstream" port at the other end. Originally, this was a "B' connector,

preventing erroneous loop connections, but additional upstream connectors were specified,

and some cable vendors designed and sold cables which permitted erroneous connections

(and potential damage to the circuitry). USB interconnections are not as fool-proof or assimple as originally intended.

The host includes 15 k pull-down resistors on each data line. When no device is

connected, this pulls both data lines low into the so-called "single-ended zero" state (SE0 in

the USB documentation), and indicates a reset or disconnected connection.

Though high bandwidth devices are commonly referred to as "USB 2.0" and

advertised as "up to 480 Mbit/s", not all USB 2.0 devices are high bandwidth.

The USB-IF certifies devices and provides licenses to use special marketing logos for

either "basic bandwidth" (low and full) or high bandwidth after passing a compliance test and

paying a licensing fee. All devices are tested according to the latest specification, so recently-

compliant low bandwidth devices are also 2.0 devices.

The actual throughput currently (2006) of USB 2.0 high bandwidth attained with real-

world devices is about two thirds of the maximum theoretical bulk data transfer rate of

53.248 MiB/s. Typical high bandwidth USB devices operate at lower data rates, often about

3 MiB/s overall, sometimes up to 1020 MiB/s.

ARCHITECTURE

ARCHITECTURAL COMPONENTS

HUB

The hub provide electrical interface between the USB devices and the host. Hubs

are directly responsible for supporting many of the attributes that make USB user friendly

and hide its complexity from the user. Listed below the major aspects of USB functionality

that hub support:


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Connectivity behavior Power management Device connect/disconnect detection Bus fault detection Superspeed and USB2.0 (high-speed, full-speed, an low-speed) support

A USB 3.0 hub incorporates a USB 2.0 hub and a SuperSpeed hub consisting of twoprincipal components: the SuperSpeed Hub Repeater/Forwarder and the SuperSpeed Hub

controller. The hub repeater/forwarder is responsible for connectivity and setup and tear-

down. It also support fault detection and recovery. The Hub controller provides the

mechanism for host-hub communication. Hub-specific status and control commands permit

the host to configure hub and to monitor and control its individual downstream port.

HOST

There are two hosts are incorporated in a USB 3.0 host. One is SuperSpeed host and the

second one is Non-SuperSpeed host. This incorporation ensures the backward compatibility

of the USB 3.0 hub. Here the SuperSpeed hub will be supporting the 500MB/sec data transfer

rate with full duplex mode. Then the Non-SuperSpeed host will be supporting the old data

rates such as High-Speed, Full-Speed, Low-Speed. The host here interacts with the devices

by the help of a host controller.

When the host is powered off, the hub does not provide power to is downstream unless

the hub support the charging application. When the host is powered on with SuperSpeed

support enabled on its downstream port by default the following is the typical sequence of

events.

Hub detects VBUS SuperSpeed support and powers its downstream ports with

SuperSpeed enabled.

Hub connects both as s SuperSpeed and as a High-Speed device.

Device detects VBUS and SuperSpeed support and connects as a SuperSpeed device.


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Host system begins hub enumeration at high-speed and SuperSpeed. Host system begins device enumeration at SuperSpeed.

A SuperSpeed host is a source or sink of information. It implements the requiredhost-end, SuperSpeed. Communications layer to accomplish information exchanges over

the bus.

It owns the SuperSpeed data activity schedule and management of the SuperSpeed

bus and all devices connected to it. The host includes an implementation number of the

root downstream ports for SuperSpeed and USB 2.0. Through these ports the host:

Detect the attachment and removal of USB device Manages control flow between the host and the USB device Manages data flow between the host and the USB device Collect the status activity statistics Provide power to the attached USB device

DEVICE

SuperSpeed devices are sources or sink of information exchanges. They implement

the required device-end, SuperSpeed communication layers to accomplish information

exchanges between a driver on the host and a logical function on the device. All SuperSpeed

devices share their base architecture with USB 2.0.

They are required to carry information for self-identification and generic

configuration. They are also required to demonstrate behavior consistent with the defined

SuperSpeed Device States.

All devices are assigned a USB address when enumerated by the host. Each device

supports one or more pipes though which the host may communicate with the device.

All devices must be support a designed pipe at endpoint zero to which the devices

Default Control Pipe is attached. All devises support a common access mechanism for

accessing information through this control pipe.

The USB 3.0 supports an increased power supply for the devices operating at the


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Architecture of USB 3.0

SuperSpeed. USB 3.0 devices within a single physical package (ie, a single peripheral) can

consist of a number of functional topologies including single function , multiple functions on

a single peripheral device (composite device), and permanently attached peripheral devices

behind an integrated hub.


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APPLICATIONS

The USB ports are used for a number of applications. The USB ports get the

popularity because of its simplicity as well the easiness in use. The main application of USB3.0 is listed below.

USB implements connections to storage devices using a set of standards called theUSB mass storage device class (referred to as MSC or UMS). This was initially

intended for traditional magnetic and optical drives, but has been extended to support

a wide variety of devices, particularly flash drives. This generality is because many

systems can be controlled with the familiar idiom of file manipulation within

directories (The process of making a novel device look like a familiar device is also

known as extension)

USB 3.0 can also support portable hard disk drives. The earlier versions of USBswere not supporting the 3.5 inch hard disk drives. Originally conceived and still used

today for optical storage devices (CD-RW drives, DVD drives, etc.), a number of

manufacturers offer external portable USB hard drives, or empty enclosures for

drives, that offer performance comparable to internal drives.

These external drives usually contain a translating device that interfaces a drive ofconventional technology (IDE, ATA, SATA, ATAPI, or even SCSI) to a USB port.

Functionally, the drive appears to the user just like an internal drive.

These are used to provide power for low power consuming devises. These can beused for charging the mobile phones.

Though most newer computers are capable of booting off USB Mass Storage devices,USB is not intended to be a primary bus for a computer's internal storage: buses such

as ATA (IDE), Serial ATA (SATA), and SCSI fulfill that role. However, USB has

one important advantage in that it is possible to install and remove devices without

opening the computer case, making it useful for external drives.


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Mice and keyboards are frequently fitted with USB connectors, but because most PCmotherboards still retain PS/2 connectors for the keyboard and mouse as of 2007,

they are often supplied with a small USB-to-PS/2 adaptor, allowing usage with either

USB or PS/2 interface.

Joysticks, keypads, tablets and other human-interface devices are also progressivelymigrating from MIDI, PC game port, and PS/2 connectors to USB.

It can also support Ethernet adapter, modem, serial port adapter etc It can support Full speed hub, hi-speed hub, and SuperSpeed hub. It can support USB smart card reader, USB compliance testing devices, Wi-Fi

adapter, Bluetooth adapter, ActiveSync device, Force feedback joystick

CONCLUSION

The Universal serial bus 3.0 is supporting a speed of about 5 Gb/sec ie ten times faster

than the 2.0 version. And it is also faster than the new Firewire product S3200. So hopefully

by the help of this SuperSpeed data transfer rate the USB 3.0 will be replacing many of the

connecters in the future. The prototype of the USB 3.0 was already implemented by ASUSE

in their motherboard. The drivers for the USB 3.0 are made available to the opensource

Linux. The Linux kernel will support USB 3.0 with version 2.6.31, which will be released

around August. Because of the backward compatibility of the USB 3.0 the devises which weare using now and the ports we are using now(which is USB 2.0) will be working proper with

the new USB 3.0 devises and ports. Consumer products are expected to become available in

2010. Commercial controllers are expected to enter into volume production no later than the

first quarter of 2010.


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REFERENCES

USB 3.0 specifications released by USB consortium

http://www.reghardware.co.uk/superspeed_usb_3_guide

http://en.wikipedia.org/wiki/Universal_Serial_bus

http://www.usb.org/developers/ssusb

http://www.usb.org/developers/docs

http://www.wired.com/gadgetlab/2008/11/superspeed-us-1

http://tech.blorge.com

http://www.interfacebus.com

http://www.everythingusb.com/superspeed-usb.html

http://www.youtube.com

Documentation of USB 3.0

Documents

Transcript of Documentation of USB 3.0